The roles of added chlorine and sulfur on ash deposition mechanisms during solid fuel combustion
Journal article, 2021

The focus of this paper is on effects of chlorine and sulfur on coal ash deposition rates, under practically relevant but systematically controlled combustion conditions. This problem is important, not so much for coal, but to understand and predict deposition rates for biomass combustion where chlorine contents can be high. To this end, ash deposition rates on a controlled temperature surface were measured for controlled amounts of chlorine and sulfur added to a pulverized coal, doped with potassium and burned in a 100 kW rated combustion rig. Previous work with 35 tests on 11 coal, biomass and petroleum coke fuels burned under a range of operating conditions had strongly suggested that the deposition rate of the tightly bound inside deposits was independent of the ash aerosol composition, and depended only on PM1 in the flue gas. The loosely bound outside deposition rate was dependent primarily on the total alkali content in the flue gas. The new results using chlorine added to the fuel (in the form of ammonium chloride) required these previous conclusions to be drastically revised. They showed that chlorine, not alkali alone, had large effects on the deposition rate of the inside deposits, which now were orders of magnitude higher than without chlorine addition, and did not fit previous (multi-fuel) correlations with PM1. Sulfur addition, together with chlorine, did not affect deposition rates much, although it did lower the chlorine content of the deposit. These results are interpreted in terms of the ash aerosol size segregated composition, which was also measured, and potential sulfation reactions within the deposit.


Ash deposition

Chlorine and sulfur


Xiaolong Li

University of Utah

Yueming Wang

Southeast University

University of Utah

Thomas Allgurén

Chalmers, Space, Earth and Environment, Energy Technology

Klas Andersson

Chalmers, Space, Earth and Environment, Energy Technology

Jost O.L. Wendt

University of Utah

Proceedings of the Combustion Institute

1540-7489 (ISSN)

Vol. 38 3 4309-4316

Subject Categories

Chemical Process Engineering

Chemical Engineering


Chalmers Power Central



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